(1.)Someone Who thinks they knew how to do something but actually just screwed everything up. (2.)Someone who goes into a serious explanation of doing something fairly simple or unimportant like how to drive a bumper car. (3.) When something just doesn't work how you want it to. (4.) an Idiot...Nub

for 1st def:

Person: Man I really need to fix my computer.

Expert: No problem I'll help.

Person: You freakin EXPERT! You just erased my hard drive.

2nd def:
*In line to ride the bumper cars*

Expert: Now son you need to get a little distance so you can pick up speed then you want to hit them in the side.....ect.

*also in line behind expert watching him talk to his son*

Person: Expert bumper cars! Dang leave the kid alone.

3rd def:

*trying to call a friend and your cell phone says the network is busy* after the third time....

Person: expert network busy..Dang!
or when friend answers you can call him expert network busy!